Motorized debris-collecting devices were first developed in the early 20th century. Since the first motorized street sweeper was put into use in 1914, there have been numerous modifications, improvements, and variations in the design of debris collection devices. U.S. Pat. Nos. 4,206,530, 4,615,070, and 5,943,733, for example, describe debris-collecting vehicles having several common features, including a brush debris collection system, a filter, a hopper for containing collected debris, and a vacuum for moving debris through the vehicles. While somewhat effective for debris collecting, such debris collection systems and vehicles suffer from various limitations that restrict their usefulness in the handling of collected debris. For example, vacuum systems of such devices may cause such devices to be incapable of effectively moving large debris throughout the device (e.g., to the hopper and/or through the filter). As such, the vehicles of the '530, '070, and '733 patents may be incapable of effectively handling larger and/or heavier debris, and the placement of the hopper in such devices is usually restricted to near the debris collection system.
An additional problem associated with the use of many known debris collection devices (particularly, street sweepers) is the need to spray liquid (typically water) during debris collection. The use of water or other liquids can be undesirable, particularly in colder climates where water may freeze forming ice on the cleaned surface. Several “waterless” sweeper systems have been developed in an effort to address these problems. For example, U.S. Pat. Nos. 4,754,521 and 4,884,313 describe sweepers that attempt waterless debris collection. In particular the '521 and '313 patents describe street sweepers comprising a roll brush debris collection system, a vertical paddle-based conveyor belt for delivery of collected debris, and a hopper containing a filtration system. Although capable of substantially waterless debris collection, such debris collection vehicles are often inefficient in the handling of collected debris. For example, the design of these sweepers requires inefficient use of the filter due to its placement in the hopper. The use of a paddle-based vertical conveyor system and non-focused vacuum suction also can cause operational inefficiencies.
For these and other reasons, there is a need for improved and alternative debris collection systems, vehicles incorporating such systems, and methods of debris removal and handling. The invention provides such systems, vehicles, and methods. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.